The invention relates to a transmission system comprising a phase-locked loop which includes
a phase comparator for comparing an oscillator signal with a reference signal and for generating a comparison signal, and PA1 an oscillator which is provided for receiving a control signal derived from the comparison signal.
Such a transmission system in which data of an incoming signal are written in a buffer is known from EP 0 404 268 A2. The data read from the buffer form an outgoing signal. A write address generator (for example a counter) generates write addresses for writing data in the buffer. For this purpose, the write address generator is supplied with a write clock signal derived from the incoming signal. The read operation is controlled by a read address generator (for example, a counter) which receives a read clock signal. Justification and control data occurring in the incoming signal are not further transported in the outgoing signal by the transmission system. A subtraction of the write and read addresses is then effected which yields a reference signal for a phase-locked loop. The phase-locked loop which comprises a phase comparator and an oscillator forms the read clock signal based upon the comparison between the reference signal and the oscillator signal in the phase comparator, from which comparison signal the read clock signal is derived.
The phase-locked loop used in the transmission system still utilizes components for which it is impossible to integrate them with the technology in which the other components of the transmission system are realised. The phase-locked loop comprises components in ECL technology and further discrete components, whereas the other components of the transmission system are integrated in CMOS technology in at least one integrated circuit.
Therefore, it is an object of the invention to provide a transmission system of the type defined in the opening paragraph, in which the essential components of the phase-locked loop are realised in the same technology as the other components of the transmission system.